(1) Field of the Invention
This Invention relates to a turbine, in which a rotor within a casing is rotatable by fluid.
(2) Description of the Prior Art
According to a conventional turbine, a moving fluid is jetted toward a plurality of vanes from a nozzle fixed on a casing to rotate them high-speedily.
To obtain a powerful rotary force in a conventional turbine, it is necessitated to enlarge the diameter of each vane, but the strength of the rotary force is restricted. Even in a restricted rotary force, the velocity of the shaft rotation is so rapid that it must be reduced by a speed reducer. Thus, the shaft rotation is placed in a condition of high torque at a lower speed.
Further, each vane in a conventional turbine comprises a convex surface having a positive torque and a convex surface having a negative torque, so that a certain torque offset by the positive torque and the negative torque takes place. Namely, the moving fluid traversing between adjacent vanes forms a resistance to flow.
Further, there exist a number of spaces between a casing and a plurality of vanes, so that a wasteful outflow of a certain quantity of the moving fluid is unavoidable.
Further, the speed reducer must be provided with a high precision tooth profile.
Still further, it is required to install other auxiliary devices, so that the manufacturing and operating cost of the turbine becomes expensive.
In spite of such disadvantages, the conventional turbines are used at present because they have a high thermal efficiency and a long time operability.
In the present stage, any other turbine that have overcome the aforesaid disadvantages and inconveniences does not exist.